The present invention relates to the display field, and more particularly to a naphthalene derivative that can be used in the preparation of an organic electroluminescent device that is a kind of display, a material for an organic electroluminescent device, which includes the same, and an organic electroluminescent device including the same.
Organic semiconductors have been developed for application to various kinds of many electronic systems. Organic electroluminescent devices have a simple structure, various advantages in their preparation process, high luminance, excellent viewing angle characteristics, fast response speeds, and low driving voltages, compared to other flat panel display devices such as liquid crystal displays (LCDs), plasma display panels (PDPs) and field emission displays (FEDs). By virtue of these advantages, organic electroluminescent devices have been actively developed for use as light sources for backlight units for displays or flat panel displays such as wall-mounted televisions, lighting devices, advertizing boards and the like.
Generally, when voltage is applied to an organic electroluminescent device, a hole injected from the anode and an electron injected from the cathode are recombined to form an exciton that is an electron-hole pair, and the energy of the exciton is transferred to the light-emitting material and converted into light.
Since a low-voltage driving organic electroluminescent device including an organic thin film laminated between two opposite electrodes in order to increase the efficiency and stability of the organic electroluminescent device was reported by C. W. Tang et al. of Eastman Kodak Company (C. W. Tang, S. A. Vanslyke, Applied Physics Letters, Vol. 51, pp. 913, 1987), studies on organic materials for organic electroluminescent device having a multilayered thin film structure have been actively conducted. Further, Japanese Patent Laid-Open Publication No. 1996-012600 discloses a device including a phenyl anthracene derivative as a light-emitting material. This anthracene derivative is used as a blue light-emitting material, but more highly efficient light emission has been required.
Meanwhile, the stability of thin films has been required to increase the lifetime of devices, and improvement in conventional anthracene derivatives has been required, because these derivatives are frequently crystallized so that thin films including these derivatives are broken. For example, U.S. Pat. No. 0,593,571 discloses a dinaphthyl anthracene compound. However, because this compound has a horizontally and vertically symmetrical molecular structure, it is easily aligned and crystallized during high-temperature storage and high-temperature driving. In addition, Japanese Patent Laid-Open Publication No. 2000-273056 discloses a horizontally asymmetrical allyl anthracene compound, but this compound cannot be prevented from being crystallized, because a group that is substituted with anthracenediyl is a simple phenyl or biphenyl group.
Accordingly, the present inventors have conducted studies on aromatic compounds capable of achieving a low driving voltage, excellent color purity, high luminous efficiency, high heat resistance and a long lifetime, and as a result, have found that a 1,8-substituted naphthalene derivative has such characteristics, thereby completing the present invention.